Characterisation of Milk Clotting Properties of Latex from Japanese Milkweed (Metaplexis japonica)

Abstract

The crude enzyme of latex from Japanese milkweed (Metaplexis japonica) clotted 10% reconstituted skim milk, and the curd was stable with no visible collapse. Additionally, milk-clotting properties of the crude enzyme were investigated. Multiple proteases were suggested to be involved in milk clotting, and cysteine proteases played a major role. The crude enzyme showed a higher milk clotting activity under acidic conditions and at 60 °C when a reconstituted low-heat skim milk ranging from pH 5.5 to 8.0 and from 25 to 60 °C was used as a substrate, respectively. Finally, the casein hydrolysis pattern of the crude enzyme showed a similar pattern to microbial rennet (degradation primarily of κ-casein).